KR20070119005A - Quality Improvement System and Method for Real-Time Multimedia Sessions - Google Patents

Abstract

The present invention provides a system and method for improving the quality of real-time multimedia sessions wherein each endpoint of a real-time packet stream transmits (1) feedback reports that describe the quality of the stream received by the endpoint and (2) forward reports that are based on the feedback reports received by the endpoint and that describe the quality of the stream received by the other, remote endpoint. The forward reports are used by routers to re-route packets around problems in the network that are located between the router and the remote endpoint.

Description

SYSTEM AND METHOD FOR IMPROVING THE QUALITY OF REAL TIME MULTIMEDIA SESSIONS

The present invention relates to network monitoring and routing systems and methods. In particular, the present invention relates to a system and method for improving the quality of real-time multimedia sessions between endpoints in a network.

Real-time multimedia sessions, such as Voice over IP (VoIP) calls and video conferencing, depend heavily on the quality of the underlying packet transport network. Problems such as network congestion substantially affect the quality of voice or video calls and cause user complaints. The present invention provides a means for improving the quality of real time multimedia sessions.

Real-time multimedia traffic is generally transmitted in the form of Real-Time Transport Protocol-IETF RFC3550 (RTP) frames encapsulated in UDP and IP packets. Performance feedback is provided by the Real-Time Transport Control Protocol-IETF RFC3550 (RTCP) protocol, in particular the receiver reporting (RR-IETF RFC3550) and extended reporting (XR-IETF RFC3611) types.

In conventional systems, the quality of the RTP stream is measured by the receiving system Y and reported to the transmitting system X using RTCP RR or XR reports. These reports are inserted in the packet stream sent from Y to X. Therefore, the real-time multimedia packet stream includes a stream of RTP frames from one endpoint system to the second endpoint system, where the RTP frames report on the quality of the stream from the second endpoint system to the first endpoint system. Is inserted.

For example, if RTP (X, Y) represents an RTP frame sent from X to Y and RTCP (X, Y) represents an RTCP report describing the quality of the stream from X to Y, typical streams are as follows:

From X to Y:

RTP (X, Y) --- RTP (X, Y) --- RTCP (Y, X) --- RTP (X, Y) --- RTP (X, Y) --- RTP (X, Y )

From Y to X:

RTP (Y, X) --- RTP (Y, X) --- RTCP (X, Y) --- RTP (Y, X) --- RTP (Y, X) --- RTP (Y, X )

This is a common and customary use of the RTP (RFC3550) protocol.

The path taken by the packet stream from X to Y and from Y to X is independently determined by the router in the packet network. This means that the path can be different and often different from packet stream. For example, FIG. 1 can be taken for a packet to travel from endpoint M to endpoint N in a network 8 comprising a plurality of nodes O, P, Q, R, S, T. One path (2) is shown. Another path 4 from endpoint N to endpoint M is also shown.

It is desirable for the routing function to be aware of congestion related problems because it can be used to influence routing decisions and cause re-routing of calls. This actually causes problems as routers generally do not know the problems that arise between the router and the receiving endpoint. For example, in network 8 shown in FIG. 1, node R, which is a router located between endpoint M and endpoint N, is not aware of the network congestion problem at node P, which is node P. Is located between node R and endpoint N on path 2. If node R is aware of network congestion problems at node P, node F may use another path, such as path 6 shown in FIG. The quality of the stream is improved. One solution is for the router R to review the performance reports coming in from the endpoint N, but this is complex to implement and the packet stream from the endpoint N to the endpoint M is endpoint M. This may not be practical if it follows a different path than the packet stream from the endpoint to endpoint N.

Conventional solutions to this problem include in the frame relay frame header a Forward Explicit Congestion Notification (FECN) bit and a Back Explicit Congestion Notification (BECN) bit that can be used to suppress traffic based on switch congestion. These bits are "binary" bits in the operation and are intended only to inform the packet source that the output should be limited. This means that for a variety of reasons: (a) the packet rate must remain constant in order to meet the delivery requirements for voice or real-time video, and (b) corrective action in multimedia applications may be rerouted or prioritized. It doesn't work in most multimedia applications because of the change in rank.

Therefore, there is a need for an improved solution to this problem that can arise in large networks.

The present invention is based on a feedback report describing the quality of the stream each endpoint of the real-time packet stream receives by (1) the endpoint and (2) the feedback report received by the endpoint This solution is provided by providing a system and method for transmitting a forward report describing the quality of a stream received by another remote endpoint.

Other objects, features and advantages will become apparent upon consideration of the following detailed description of the invention in conjunction with the drawings and claims.

1 is a relationship diagram illustrating an example of transmission paths for packets to take between endpoints in a network with multiple nodes.

2 is a relational diagram illustrating a desired transmission path for packets to be taken between endpoints in a network having a network congestion problem at one node.

3 is a relationship diagram illustrating the transmission of feedback reports between endpoints in one embodiment of the invention.

4 is a relationship diagram illustrating transmission of a feedback report and a forward report between endpoints in one embodiment of the present invention.

5 is a relationship diagram illustrating rerouting of packets to avoid network problems in one embodiment of the present invention.

Referring to FIG. 3, there is shown a network 20 comprising a first endpoint A and a second endpoint B connected through a plurality of nodes C, D, E, F, G, H. It is. The first endpoint A or second endpoint B may comprise an IP telephone, a media gateway, a video conferencing system, or the like. In operation, the first endpoint A sends the first packet stream 22 to the second endpoint B, and the second endpoint B sends the second packet stream 24 to the first endpoint. Transmit to (A) to provide real-time flow of multimedia (audio or video) packets.

A. Quality Surveillance

In the embodiment described, the first monitoring device M1 is provided to the first endpoint A and the second monitoring device M2 is provided to the second endpoint B. In other embodiments, one or two of the monitoring devices may be provided at an access point in the network, which is preferably located relatively close to each endpoint. The first and second monitoring devices M1 and M2 each comprise a performance monitoring component for monitoring the second packet stream 24 and the first packet stream 22 for quality. In one embodiment, the performance monitoring component of each monitoring device M1, M2 determines the level of at least one impairment and generates a quality measure associated with the input packet stream 22 or 24 to generate an input packet stream. Monitor (22 or 24). Such monitoring can be performed at periodic intervals, eg every 10 seconds, so that several quality measurements are produced during the transmission of the packet streams 22, 24. The failure may include, but is not limited to, packet delay, packet loss (some packets are lost or arrive too late and discarded), jitter (packet arrival time changes), or distortion. Quality measures may include, but are not limited to, average packet delay, average packet loss rate, average jitter, or average distortion.

In various embodiments, one or both of the monitoring devices are commercially available quality of service monitoring devices, such as VQmon manufactured by Telchemy, Incorporated (“VQmon”). ) "Is a trademark of Telchemy Incorporated). VQmon is a U.S. Patent No. 6,741,569, entitled "Quality of Service Monitor for Multimedia Communications System," and the name of the invention, "Dynamic Quality Monitoring System." US Patent Application No. 09 / 574,472, entitled "of Service Monitor," and US Patent Application No. 10 / 802,536, entitled "Quality of Service Monitor for Multimedia Communications System." More fully described, and these US patents are incorporated herein by reference.

By monitoring the input packet stream 22 or 24 for quality, the first and second monitoring devices M1, M2 are responsible for network problems such as congestion, node failure, or line card failure. It is possible to identify when 24) is in the transmission path taken. For example, referring still to FIG. 3, if a network problem is associated with node D, the performance monitoring component of second monitoring device M2 may be configured to include packet stream 22 received by second endpoint B, and the like. It will detect the associated high level of failure and generate a quality measure indicating that there is a network problem on the transmission path from the first endpoint A to the second endpoint B.

B. Generate Feedback Report

Each of the first and second monitoring devices M1, M2 also includes a feedback reporting component. The feedback report component of each monitoring device M1, M2 generates a feedback report describing the quality of the packet stream 22 or 24 received by the endpoint A or B. For example, referring still to FIG. 3, the feedback reporting component of the second monitoring device M2 analyzes the quality measurement generated by the performance monitoring component of the second monitoring device M2 and uses the quality measurement. To generate a feedback report 26. Accordingly, the feedback report 26 describes the quality of the packet stream 22 received by the second endpoint B. In one embodiment, the feedback reporting component copies the quality measurement produced by the performance monitoring component of the second monitoring device M2 and formats the quality measurement for inclusion in the feedback report 26. Thus, in the above example where the network 20 is having a problem, the feedback report 26 indicates that the network problem is on the transmission path from the first endpoint A to the second endpoint B. FIG.

In certain embodiments, feedback report 26 may include an RTCP RR report or an RTCP XR report. In other embodiments, feedback report 26 may be other suitable, including, but not limited to, H.323 (generated by the International Telecommunication Union), Session Initiation Protocol (SIP), or Media Gateway Control Protocol (MGCP). It may include reporting compatible with the protocols.

After generating the feedback report 26, the feedback reporting component of the second monitoring device M2 feeds back to the second packet stream 24 sent from the second endpoint B to the first endpoint A. FIG. Include report 26. In various embodiments, the feedback reports are generated at periodic intervals, such as every 10 seconds or included in the second packet stream 24, such that several feedback reports are sent from the second endpoint B to the first endpoint A. FIG. Is sent).

Similarly, referring to FIG. 4, the feedback reporting component of the first monitoring device M1 analyzes the quality measurement generated by the performance monitoring component of the first monitoring device M1 and uses the quality measurement. To generate a feedback report 28. Thus, the feedback report 28 describes the quality of the packet stream 24 received by the first endpoint A. In one embodiment, the feedback reporting component copies the quality measurement produced by the performance monitoring component of the first monitoring device M1 and formats the quality measurement for inclusion in the feedback report 28.

After generating the feedback report 28, the feedback reporting component of the first monitoring device M1 includes the feedback report 28 in the packet stream for transmission to the second endpoint B. Since packet streams are persistent and can last for several minutes, in most examples feedback report 28 will be generated in time for inclusion in first packet stream 22.

C. Generate Forward Report

The first and second monitoring devices M1, M2 further comprise a forward reporting component. The forward report component of each monitoring device M1, M2 generates a forward report based on the feedback report received by the endpoint B or A, respectively. For example, referring still to FIG. 4, the forward report component of the first monitoring device M1 may forward the forward report 32, which describes the quality of the packet stream 22 received by the second endpoint B, Generate based on feedback report 26 received by endpoint A. In one embodiment, the forward reporting component of the first monitoring device M1 copies the quality measurement previously copied and formatted by the feedback reporting component of the second monitoring device M2, and forward reporting 32. Format the quality measure for inclusion in the. Thus, in the example where the network is having problems, forward report 32 indicates that there is a network problem on the transmission path from the first endpoint A to the second endpoint B. FIG.

After generating the forward report 32, the forward report component of the first monitoring device M1 includes the forward report 32 in the first packet stream 22, at least a portion of which is the first endpoint A. ) Along the path to the second endpoint (B). In one embodiment, the forward report 32 is attached to the feedback report 28 generated by the feedback reporting component of the first monitoring device M1.

D. Packet Routing

An adaptive routing component R is provided to the router of the network 20. The adaptive routing component (R) must use a different path when (1) analyzes the forward report and (2) transmits a packet that contains a packet stream sent between endpoint A and endpoint B. Forward report analysis component for determining whether or not. The adaptive routing component further includes a rerouting component for rerouting packets in the packet stream if the forward report analysis component determines that another route should be used. In various embodiments, the rerouting component selects another route from among a set of predetermined routes, or creates another route using distance and cost algorithms known in the art.

For example, with continued reference to FIG. 4, adaptive routing component R may be provided to node F, which is a router. The forward report analysis component of the adaptive routing component R analyzes the forward report 32 generated by the first monitoring device M1 and included in the first packet stream 22, and forwarded to the forward report 32. Based on this, it is determined whether another path should be used to send packets in the first packet stream 22 and / or subsequent packet streams to the second endpoint B. In one embodiment, the forward report analysis component compares the quality measure and threshold of the forward report 32. If the quality measure exceeds the threshold, the forward reporting analysis component informs the rerouting function that it should use a different path.

In another embodiment, a third monitoring device is provided to the router for monitoring the first packet stream 22 for quality. Like the first and second monitoring devices M1 and M2, the third monitoring device monitors the input packet stream 22 by determining at least one level of failure and generating router quality measurements associated with the packet stream 22. can do. In this embodiment, the forward report analysis component compares the quality measure of forward report 32 with the router quality measure. The quality of the first packet stream 22 is much higher than the quality indicated by the forward report 32 (which indicates the quality downstream of the router) or the level of at least one fault is much lower than the quality indicated by the forward report 32. If a router quality measure (which indicates the router's quality upstream) is indicated, the forward reporting analysis component informs the rerouting function that it should use a different path.

Thus, in the example of a network problem, the forward report analysis component of the adaptive routing component R reports forward that there is a network problem on the path between the adaptive routing component R and the second endpoint B. And to predict from (32). As a result, the rerouting component uses at least one packet in the first packet stream and / or subsequent packet streams using another path, such as the path shown in FIG. 5, to avoid network problems at node D. Transmitting, thereby increasing the quality of the packet stream received by the endpoint (B).

Although the invention has been described with reference to its preferred embodiments, it should be understood that changes and modifications may be made within the spirit and scope of the invention as described herein and as set forth in the claims.

In accordance with the present invention, each endpoint of the real-time packet stream is based on a feedback report describing the quality of the stream received by the endpoint, and a feedback report received by the endpoint and received by another remote endpoint. A system and method are provided for transmitting a forward report describing the quality of a stream.

Claims (14)

A method for improving the quality of packet streams transmitted between a first endpoint and a second endpoint via a router in a network, the method comprising: a. Monitoring for quality, a first packet stream sent from the first endpoint to the second endpoint; b. Generating a feedback report describing the quality of the first packet stream; c. Including the feedback report in a second packet stream sent from the second endpoint to the first endpoint; d. Generating a forward report based on the feedback report; e. Including the forward report in a first packet stream, wherein at least a portion of the first packet stream is sent along a path from the first endpoint to the second endpoint; And f. Based on the forward report, determining at the router whether to use a different path. The method of claim 1, Determining if the other path should be used includes predicting whether there is a network problem between the router and the second endpoint, wherein the method includes: a. If it is predicted that there is a network problem between the router and the second endpoint, sending at least one packet to the first packet stream using another path to avoid the network problem. How to improve quality. The method of claim 1, Monitoring the first packet stream for quality is performed at the second endpoint. The method of claim 1, Monitoring the first packet stream comprises determining a level of at least one failure and generating a quality measure associated with the first packet stream. The method of claim 4, wherein Generating the feedback report comprises formatting the quality measure for inclusion in the feedback report, Generating the forward report comprises formatting a quality measurement from the feedback report for inclusion in the forward report. The method of claim 5, Determining whether the other path should be used comprises comparing the quality measure of the forward report to a threshold. The method of claim 5, Determining whether to use the other path comprises comparing a quality measure of the forward report to a router quality measure. A system for improving the quality of a packet stream transmitted between a first endpoint and a second endpoint in a network, the method comprising: a. A performance monitoring component for monitoring a first packet stream sent from the first endpoint to the second endpoint for quality; b. A feedback reporting component that generates a feedback report describing the quality of the first packet stream and includes the feedback report in a second packet stream sent from the second endpoint to the first endpoint; c. Generate a forward report based on the feedback report, and include the forward report in the first packet stream, wherein at least a portion of the first packet stream follows a path from the first endpoint to the second endpoint Forwarded reporting component; And d. And a forward report analysis component for determining whether to use a different path based on the forward report. The method of claim 8, The forward report analysis component is configured to predict from the forward report whether there is a network problem between the forward report analysis component and the second endpoint, The system, a. If it is predicted that there is a network problem between the forward report analysis component and the second endpoint, a rerouting component that transmits at least one packet to the first packet stream using another path to avoid the network problem. The system for improving the quality of a packet stream further comprising. The method of claim 9, The performance monitoring component is a system for improving the quality of a packet stream located at the second endpoint. The method of claim 10, The performance monitoring component is configured to determine a level of at least one failure and generate a quality measure associated with the first packet stream. The method of claim 11, The feedback reporting component is configured to format the quality measure for inclusion in the feedback report, The forward report component is configured to format a quality measure from the feedback report for inclusion in the forward report. The method of claim 12, The forward report analysis component is configured to compare the quality measure of the forward report with a threshold. The method of claim 12, The forward report analysis component is configured to compare the quality measure of the forward report with a router quality measure.

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